1
Microbiology Lab Exam 6 Questions with
Correct Answers | Updated (100% Correct
Answers)
How are thermal death point and thermal death time different?
Answer: Thermal death point is the lowest temperature that kills all
cells in a broth in 10 minutes. Thermal death time is the time
required to completely sterilize a particular volume of liquid at a
given temperature.
Is moist heat more effective than dry heat? Answer: Because of its
ability to penetrate microbial cells, moist heat kills microogranisms
by denaturing their proteins. Sterilization can be achieved at lower
temperatures in a shorter duration.
What is the thermal death time for Bacillus subtilis? Answer: 100
degrees C at 20 minutes.
What is the function of pressure in an autoclave? Answer: High
pressure helps with effective sterilization to take place.
Are some microbes more resistant to different kinds of heat than
others? Answer: Yes, some microbes, like archea have an optimum
growth temp. of 80C or higher. These organisms are called
thermophiles, and most live at hot springs, making sulfur an
important contributor to their metabolic activity.
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, 2
Define pasteurization and give its purpose. Answer: The use of heat
to kill pathogens and reduce the number of spoilage
microorganisms in food and beverages.
Why is Bacillus subtilis so resistant to the effects of heat? Answer:
Bacillus subtilis contains endospores, which makes it more resistant
to heat
What is the thermal death time and thermal death point for bacillus
subtilis? Answer: 100 C at 10 minutes. Or 20?
Bactericidal Answer: Product or item that is capable of destroying
bacteria
Virucidal Answer: Capable of destroying viruses
Fungistatic Answer: chemicals that inhibit fungal growth
Bacteriostatic Answer: Prevent microbes from growing
Virustatic Answer: Not killer but suppressor, retard viral growth
Sporicidal Answer: Capable of killing spores
Can the amount of disinfectant affect your results? Explain. Answer:
Yes. Effectiveness of chemical agents depends on time, temperature,
pH and concentration. Increased concentration equals increased
potency
© 2025 All rights reserved
Microbiology Lab Exam 6 Questions with
Correct Answers | Updated (100% Correct
Answers)
How are thermal death point and thermal death time different?
Answer: Thermal death point is the lowest temperature that kills all
cells in a broth in 10 minutes. Thermal death time is the time
required to completely sterilize a particular volume of liquid at a
given temperature.
Is moist heat more effective than dry heat? Answer: Because of its
ability to penetrate microbial cells, moist heat kills microogranisms
by denaturing their proteins. Sterilization can be achieved at lower
temperatures in a shorter duration.
What is the thermal death time for Bacillus subtilis? Answer: 100
degrees C at 20 minutes.
What is the function of pressure in an autoclave? Answer: High
pressure helps with effective sterilization to take place.
Are some microbes more resistant to different kinds of heat than
others? Answer: Yes, some microbes, like archea have an optimum
growth temp. of 80C or higher. These organisms are called
thermophiles, and most live at hot springs, making sulfur an
important contributor to their metabolic activity.
© 2025 All rights reserved
, 2
Define pasteurization and give its purpose. Answer: The use of heat
to kill pathogens and reduce the number of spoilage
microorganisms in food and beverages.
Why is Bacillus subtilis so resistant to the effects of heat? Answer:
Bacillus subtilis contains endospores, which makes it more resistant
to heat
What is the thermal death time and thermal death point for bacillus
subtilis? Answer: 100 C at 10 minutes. Or 20?
Bactericidal Answer: Product or item that is capable of destroying
bacteria
Virucidal Answer: Capable of destroying viruses
Fungistatic Answer: chemicals that inhibit fungal growth
Bacteriostatic Answer: Prevent microbes from growing
Virustatic Answer: Not killer but suppressor, retard viral growth
Sporicidal Answer: Capable of killing spores
Can the amount of disinfectant affect your results? Explain. Answer:
Yes. Effectiveness of chemical agents depends on time, temperature,
pH and concentration. Increased concentration equals increased
potency
© 2025 All rights reserved
